This invention relates to the fabrication of a panel structure, and, more particularly, to the fabrication of a panel structure having embedded layers with selected electrical or magnetic properties.
In a number of applications, it is necessary that a panel exhibit particular electrical and/or magnetic properties, as well as being structurally strong. An example is skin panels for use in low-observables military aircraft or other vehicles having multiple, spaced-apart layers embedded within the structural skin, with each of the layers having particular electrical properties. In other applications, embedded electrically conductive or magnetic layers are useful for de-icing, lightning-protection, radome, or sensor roles. The design of the spaced-apart active layers--their specific locations, thicknesses, morphologies, and properties--depends upon the application, and such designs are known in the art. The present invention is concerned with the fabrication of such structures, not their design.
In the past, such structures have been fabricated by several techniques. In one, conductive fibers are placed into sheets of a substrate material to form an active layer, taking care to orient the individual conductive elements in desired patterns, and the sheets are laminated together with structural sheets. This approach is tedious and expensive, and it is difficult to obtain the exact patterns of fibers required for some applications. In another approach, coatings are placed onto exposed surfaces of structures. This technique is not suitable for producing embedded conductive layers with carefully controlled properties and patterns. In another approach, conductive patterns are imprinted on thin plastic sheets, such as by silk screening onto polyethylene sheets, and the imprinted sheets are laminated together with base structure. The problem with this approach is that control of the properties of the conductive pattern is difficult, and the conductive pattern is necessarily quite thin. Such materials may also be made by patterning the surface layers or sides of honeycomb materials, an expensive undertaking which is also limited as to the thickness of the conductive pattern.
There is a need for an improved approach to the fabrication of structures with embedded layers having selected electrically conductive or magnetic properties. The present invention fulfills this need, and further provides related advantages.